This invention relates to a lubricating system for an outboard engine and more particularly to a compact pressure lubricating system for a two-cycle type of engine.
As is well known, most outboard motor engines are of the two-cycle type and are positioned with their crankshafts extending vertically. Such an arrangement gives rise to certain difficulties in connection with the provision of an adequate lubricating system, particularly if it is desired to operate the engine without the necessity of mixing the lubricating oil with the fuel. In such arrangements, the separate crankcase chambers associated with each cylinder must be sealed from each other. It has been the practice to provide an oil pump driven by the crankshaft for providing lubricating oil to the mechanisms of the individual cylinders. With such an arrangement and wherein the crankshaft is vertically disposed, the provision of a separate gear driven pump, with engines of the type previously proposed, necessitates undue elongation of the engine. In one type of arrangement the oil pump is positioned at the top of the crankcase adjacent the flywheel magneto. This obviously increases the heighth of the engine and, furthermore, due to the elevation of the oil pump, there is a possibility that it will not be supplied with oil when the boat is undergoing an abrupt maneuver. That is, the oil inlet to the pump may be disposed above the oil line so that the pump has a tendency to draw air under such conditions. Although these problems can be reduced by positioning the oil pump below the lowermost cylinder of the engine, the length of the engine nevertheless is undesireably increased.
Although it has been proposed to provide the pump drive gears for such an engine adjacent one of the crank journals, the previously proposed solutions of this type have not been completely successful. As has been noted above, it is necessary to provide a seal between adjcent crank chambers and this gives rise to difficulties in providing sufficient lubricating oil for the pump drive gears and also to insure that the pump will also be continuously supplied with lubricating oil for delivery to the engine. Also, the previously proposed arrangements have necessitated lengthening of the crankshaft in any event.
It is, therefore, a principal object of this invention to provide an improved lubricating system for an internal combustion engine. It is a still further object of this invention to provide a pressure lubrication system for a two-cycle engine having a vertically disposed crankshaft in which elongation of the crankshaft is avoided.
It is a still further object of this invention to provide a lubrication system for a two-cycle engine having a vertically disposed crankshaft which will insure aequate lubrication under all conditions.